1. Field of the Invention
The present invention relates to a video hard copy device and a method of setting printing condition thereof for fetching video signals supplied from a host computer to a dislay such as a cathode ray tube and printing out an image or characters as appeared in the display on a printing paper.
2. Description of the Related Art
A conventional video hard copy device will be described with reference to FIG. 8.
A conventional video hard copy device comprises an input interface 21 interposed between a host computer HCPU and a display such as a cathode ray tube (hereinafer referred to as CRT) for receiving color video signals and converting them into digital image data having respectively a weight of 8 bits, an image memory 22 connected to the input interface 21 for receiving the digital image data, a printing portion 25 composed of an RGB/YMC color converting circuit 23 for receiving each picture of digital image data and a printing head 24, a printing control circuit 26 having a microcomputer therein and connected to the input interface 21 and the printing head 24 for receiving and supplying data and to the image memory 22 and the RGB/YMC color converting circuit 23 for supplying data thereto and input device 27 connected to the printing control circuit 26.
The input interface 21 fetches a red video input signal R, a green video input signal G and a blue video input signal B respectively for use in one frame among those supplied from the host computer HCPU to the display CRT and converting these color video input signals R, G and B into a red digital data R.sub.D, a green digital data G.sub.D and a blue digital data B.sub.D for use in one frame. The image memory 22 having frame memories 22R, 22G and 22B receives these color digital data R.sub.D, G.sub.D and B.sub.D and sets these color digital data in the frame memories 22R, 22G and 22B. After completion of storage of these color digital data in the image memory 22, these color digital data are successively supplied to the RGB/YMC color converting circuit 23 where these color digital data are converted into color data for printing. The printing head 24 receives the color data from the RGB/YMC color converting circuit 23 and prints out the color data on a printing medium.
The arrangement will be described more in detail.
When a certain color of a part of the image as appeared on the display is replaced by another color and printed out on the printing paper by the printing portion 25, it is possible to convert one of the basic eight colors, i.e. white (W), red (R), green (G), blue (B), cyan (C), magenta (M), yellow (Y), black (Bk) as the color of the part of the image into another color among the basic eight colors by specifying a numerical value but it is impossible to convert an arbitrary color of the image as appeared on the display, particularly neutral tints, into another arbitrary color and print out such color on the printing paper.
There was a problem that a compound color of the image other than the specified color appeared on the display is converted into another compound color if the former contains any of basic eight colors which is specified to be converted. That is, there was a problem that a background color of the picture on the display, e. g. a bright gray background color of the picture on the display is printed out as a dark gray background color, when black (Bk) is specified to be replaced by white (W) and white (W) is specified to be replaced by black (Bk) in order to convert black letters alone in the picture on the display into white letters.